GOODWILL: (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Goodwill
Goodwill at the beginning of year		$ 592,731
Arbor Adjustment	$ (21)
Change in foreign currency translation adjustment		135
Goodwill at the end of year	592,845	592,845
U.S.
Goodwill
Goodwill at the end of year	581,170	581,170
APAC
Goodwill
Goodwill at the end of year	11,675	11,675
Marketing Services
Goodwill
Goodwill at the beginning of year		118,890
Arbor Adjustment	0
Change in foreign currency translation adjustment		94
Goodwill at the end of year	118,984	118,984
Marketing Services | U.S.
Goodwill
Goodwill at the end of year	110,910	110,910
Marketing Services | APAC
Goodwill
Goodwill at the end of year	8,074	8,074
Audience Solutions
Goodwill
Goodwill at the beginning of year		273,448
Arbor Adjustment	0
Change in foreign currency translation adjustment		0
Goodwill at the end of year	273,448	273,448
Audience Solutions | U.S.
Goodwill
Goodwill at the end of year	273,448	273,448
Audience Solutions | APAC
Goodwill
Goodwill at the end of year	0	0
Connectivity
Goodwill
Goodwill at the beginning of year		200,393
Arbor Adjustment	(21)
Change in foreign currency translation adjustment		41
Goodwill at the end of year	200,413	200,413
Connectivity | U.S.
Goodwill
Goodwill at the end of year	196,812	196,812
Connectivity | APAC
Goodwill
Goodwill at the end of year	$ 3,601	$ 3,601